NO.IRS: TC 41-97

INDIAN RAILWAY STANDARD SPECIFICATION FOR POLYTHENE

INSULATED POLYTHENE SHEATHED JELLY FILLED TEPEHONE

CABLE WITH POLY-AL MOISTURE BARRIER.

0. FORWARD:-

0.1 This specification is issued under the fixed serial No. IRS: TC 41 followed by

the year of original adoption as standard or in the case of revision, the year of

last revision.

ADOPTED 1990, FIRST REVISION 1997.

0.2 This specification requires reference to the following standard specification:

TEC NO. G/ Solid polythene insulated fully filled, polythen sheathed

CUG-01/02 underground telecom cable.

FEB. 96

IEC: 28 International standard of resistance for copper.

IS: 3975 Mild steel wires, formed wires and tapes for armouring

of cables.

IS: 2633 Method for testing uniformity of coating on zinc coated

articles.

BS: 6234 Polythene insulation & sheath of electric cables.

ASTM: D-1047 Cold bend test.

ASTM: D-1693 Test method for environmental stress cracking of

ethylene plastics.

ASTM: D-1169 Test method for specific resistance (resistivity) of

electrical insulating liquids.

VDE: 0472/6.65 Recommendations for testing insulated cables &

flexible cords.

ASTM: D-1248 Polythene plastics moulding and extrusion materials.

ASTM: D-883 Definition of terms relating to plastics.

IS: 9938 Recommended colours for PVC insulation for LF wires

and cables.

IS: 12444 Continuously cast and rolled electrolytic copper wire

cods for electrical conductors.

TEC No. G/ Wooden cable drum for telecom cables.

CBD-01/02.

NOV 94.

0.3 Wherever in this specification any of the above mentioned specifications are

referred to by number only the latest issue of that specification is implied;

wherever the year of issue is mentioned, the particular issue referred to is

meant.

1. SCOPE:

1.1 This specification covers the requirements and provisions of tests and

inspection of twisted pair underground telecom cable with solid polythene

(medium or high density) insulated copper conductors, fully filled core with

water resistance compound and with poly-Al laminate moisture barrier bonded

to the polythene sheath.

1.2 This specification deals with the technical requirements and does not include

all the terms and provisions of the contract.

1.3 Cable shall be manufactured in cable sizes from 10 pair to 200 pairs with

nominal conductor dia. 0.5, 0.63 and 0.9 mm. The standard cable sizes shall

be 10, 20, 50, 100 and 200 pairs. Typical cross-section of 20 pair cable is

shown in Fig. 1.

2. NUMBER OF PAIRS:

2.1 The cable shall be of different sizes varying from 10 to 200 pairs with nominal

conductor dia 0.5 or 0.63 or 0.9 mm. The standard cable sizes shall be 10, 20,

50, 100 and 200 pairs armoured/ unarmoured.

3. CONDUCTOR:

3.1 Each conductor shall consist of solid round wire of annealed high conductivity

copper, smoothly drawn, nominally circular in section, uniform in quality and

resistance, and free from defects. The quality of copper shall conform to IEC–

28 or IS – 12444.

3.2 The joints in the conductor shall be either brazed or welded and shall be kept

to a minimum and shall fulfill the following conditions:

3.2.1 The resistance of a 100 cm length of conductor containing joint sample of

conductor not containing a joint.

3.2.2 The tensile strength of 25 cm length of conductor containing a joint shall be

not less than 90% of that of an adjacent sample of conductor not containing a

joint.

3.3 The resistance of conductors and the tolerance on the individual values shall

meet the requirements of Table-1. The temperature correction factor is

indicated in Table – 2.

4. INSULATION:

4.1 Each conductor shall be insulated with solid polythene of one of the type

specified below:

4.1.1 Conductor insulation shall be polythene insulating grade and 100% virgin

material as per ASTM – D 883.

4.2 Insulation shall be materials adequately stabilized with an anti oxidant/ copper

inhibitor system sufficient to pass the oxidation induction and other relevant

tests stipulated in this specification.

4.3 The polythene shall conform to ASTM-D 1248 type II or type III, class ‘A’,

category 4 or 5 and meet the parameters detailed below:

i) Density Type II (0.926 to 0.940 gm/cc)

Type III ().941 to 0.956 gm/cc)

ii) Flow rate (melt flow Maximum 1.0 gm/10 minutes (190C.

index) 2160 gm load)

iii) Dissipation factor Maximum 0.0005

( power factor )

iv) Dielectric constant or Maximum 2.35

permittivity

v) Volume resistivity Minimum 1 x 1015 ohm-cm.

4.4 The insulation shall be uniform and smooth, and shall be coloured as in Table

– 4. The colour shall be identifiable under normal lighting conditions and

shall generally conform to IS: 9938.

4.5 The grade of pigment used for colouing the polythene shall be such that the

coloured insulation meets the specified requirements.

4.6 The thickness of insulation shall be reasonably uniform to enable the

completed cable to meet the electrical and mechanical requirements of the

specifications.

4.7 The insulated conductor shall be subjected to spark test at 4.5 KV DC or 3 KV

AC RMS for all conductor sizes. There shall not be more than 1 spark over

per 5 Km of the insulated conductor, when assessed on a monthly basis on the

insulating line. The test will be at extrusion stage.

5. TWINING/ PAIRING:

5.1 Two insulated conductors shall be twisted together with uniform lay to form a

pair. The length of the lay of any pair shall be different from that adjacent

pairs. The lay of various pairs shall be so chosen as to satisfy the capacitance

unbalance tests requirements as per cl. 25.6 and cross talk requirements as per

cl. 25.7 of this specification. To the extent possible the lay of any pair may be

limited to 150 mm.

6. UNIT:

6.1 A number of twisted pairs laid up to form a group shall constitute the unit.

6.2 The colour scheme of pairs and wires in a unit shall be in accordance with the

table no. 4 for identification.

6.3 The different colours of the binder tape shall be readily distinguishable under

normal lightening conditions. The colour scheme of binder tape shall be in

accordance with Table 3 for unit identification.

7. CABLE CORE/ STRANDING:

7.1 In cables having 10 pairs, 20 pairs, the twisted pairs shall be assembled to

form a symmetrical core. Polythene strings of required diameter may be used

as fillers if necessary for proper circular core formation.

7.2 In cables having 50 and 100 pairs, the twisted pairs shall be arranged in units

of 10 pairs, and 20 pairs respectively. An open helical lapping of 0.02 mm

minimum polyster/ poly-propylene/ polythene tape shall be applied over each

unit. The tapes shall be coloured in accordance with Table 3 and shall have

lay not exceeding 100 mm. This tape is not necessary on the 10 pairs and 20

pairs cables.

7.3 The 50 pairs cable shall have 5 units of 10 pairs and 100 pairs cable 5 units of

20 pairs. These units shall be stranded into a compact and symmetrical cable.

The sequence of the units in the cable shall be same throughout the length of

the cable.

7.4 4 Nos. of 50 pairs super unit shall be assembled to form a 200 pair cable.

7.5 Cable with any defective pair will not be acceptable.

8. FILLING COMPOUND (PETROLEUM JELLY):

8.1 The cable core shall be fully filled with a suitable water resistant compound

like jelly which is fully compatible with the polythene insulation, binders and

tapes used in the cable. It shall be of homogenous and uniformly mixed

material containing an anti-oxidant. it shall not contain dirt, metallic particles

or other foreign matter. The compatibility between the polythene and filling

compound shall be established by the tests as per cl.17 of this specification.

The compability shall be assessed for each colour of insulation in Table – 4.

9. CORE WRAPPING:

9.1 After application of the water resistant filling compound, a closed helical or

longitudinal lapping of a non – hygroscopic and non-wicking polyester tape or

tape of any other suitable material shall be laid over the cable core. The tape

may be impregnated or flooded with jelly to meet the water penetration test

requirements. Application of a flooding compound below and above the core

wrapping tape is recommended.

10. POLY-AL LAMINATE MOISTURE BARRIER/ SCREEN:

10.1 Polythene coated aluminium tape shall be applied longitudinally on the core

with a minimum overlap of 6 mm. The thickness of the aluminium tape shall

be 0.2 mm 10% and that of polythene/ co-polymer coating on each side

0.05 mm nominal. The thickness of composite tape shall be 0.3 mm 15%.

10.2 The laminate shall be bonded to the inner surface of the polythene sheathing

extruded over it any suitable method. The poly-Al laminate shall be

mechanically and electrically continuous through out the length of the cable.

For achieving/ improving the specified reduction factor, the manufacturers

may use corrugated poly-Al tapes.

11. SHEATH:

11.1 Cable shall be sheathed with polythene grade 03C or HO3C as per BS: 6234,

and containing a suitable anti-oxidant system. The material shall be virgin as

per ASTM-D-883 and meet the requirement specified below:

i) Melt flow index Shall not be more than 1.0 g/10 minute (190C, 2160 g

load)

ii) Density For 03C, shall be 0.910 to 0.940 gm/cc.

iii) Antioxidant OIT test in a copper pan at 199C as per the method in

Annexure-A (V) and the value to be recorded; the value

should be such that the requirement of cl. 20.8 of this

specification is met.

11.2 The sheath shall be reasonable circular, and free from pin holes, joints and

other defects. The variation between the maximum and the minimum

diameter at any cross section shall conform to the following:

Specified maximum diameter over Maximum variation

sheath (mm) (mm)

----------------------------------------- -------------------------

Upto 40 3 . 0

Above 40 4 . 0

11.3 The thickness of the sheath shall conform to Table – 5. The minimum

thickness shall not be less than 75% of the specified nominal value. The

average of six measurements at each end, equally placed around the

circumference, shall not be less than 85% of the specified nominal value.

11.4 The sheath shall be spark tested at the voltage given in Table-6. There shall be

no spark over. This is an on line test.

12 ARMOURING:

12.1 BEDDING: Two close helical lapping of polythene or polypropylene tape

shall be applied over inner sheath to provide sufficient mechanical 5%

overlap. The second tape shall cover the overlap of the first tape about evenly.

The width of tape is left to the discretion of the manufacturer.

12.2 ARMOUR: The sheathed cable shall then be armoured with two

applications of galvanised steel tape conforming to IS: 3975, each applied

helically in the same direction with a gap in the first tape of 28% 10% of the

width of the first tape. In any case the overlap of the second tape over the first

tape shall not be less than 20% of the width of the tape. Manufacturer may

increase the number of steel tapes & their thickness so as to meet the

requirement of reduction factor (cl. 25.9). However, the thickness of any of

the galvanised steel tapes used in two applications including zinc coating on

each tape shall not be less than 0.5 mm.

12.3 The steel tape of required width shall be galvanised; it should not be slit to a

smaller width after galvanisation, as in that case, there will not be zinc coating

on the cut edge/ edges.

12.4 Joints in the armouring tape shall be kept to the minimum. Wherever joints are

made, adequate corrosion protection shall be provided on both the sides. If

any rusty portions are noticed on the tape, the same should be painted with

suitable anticorrosive paint. When joints in tapes are necessary they shall be

made by brazing or welding and any irregularity shall be removed.

13. JACKET:

13.1 The physical/ mechanical test on jacket.

13.2 The armoured cable shall be tightly jacketed with polythene conforming to the

requirements as specified for sheath in cl. 11.0. The nominal thickness of the

jacket shall be as per Table-7. The minimum and average thickness shall be

same as in cl. 11.3.

13.3 The jacket shall be reasonably circular, free from pin holes and other defects.

13.4 The jacket shall be spark tested as per Table-7. There shall be no spark-over.

This is an on line test.

14. MECHANICAL TESTS ON CONDUCTOR:

14.1 Physical Tests for Conductor:

14.1.1 Dimensions: The diameter of the conductor shall be measured on a sample

from the finished cable. The measurements shall be made at least three

different points along the length of the sample. The value shall be in

accordance with Table-1.

14.1.2 Annealing: Test: When a sample wire of 250 mm long taken from the

completed cable is slowly and steadily stretched, elongation at fracture shall

not be less than appropriate value given in Table-1.

15. TESTS ON FILLING COMPOUND:

15.1 Stability: When held at a temperature of 65 1 c for 5 days, the

compound shall not show any separation of the constituents of the filling

compound. The test shall be conducted as per method outlined in Annexure

‘A’ (I).

15.2 Colour: The compound shall not obscure the identification of the colour

of the insulation of the conductors.

15.3 Handling: The compound shall be readily removable from the insulated

conductors by wiping. It shall be free from unpleasant odour and have no

toxic or dermatic hazards. Supplier’s certificate shall be submitted by the

cable manufacturer.

15.4 Volume Resistivity: The volume resistivity measured at 100C by the

method described in ASTM-D1169 or any other approved method shall not be

less than 1 x 1010 ohm-cm.

15.5 Permittivity: The permittivity at 1 MHz when tested as per ASTM D-924

shall not be greater than 2.3 at 20C.

15.6 Flash Point: The flash point of the filling compound when tested as per

ASTM D-92, shall not be less than 200C.

16. TESTS ON INSULATED CONDUCTORS:

16.1 Resistance to Compression: Two lengths of insulated conductor shall be

uniformly twisted under light tension so that there are 10 x 360 twists in a

length of 100 mm. Not more than 50 mm in the middle of the twisted pair shall

be placed between tow flat rigid plates coated with polythene on the inside

surface. A compressive force of 200 N (min) shall be applied between the

plates. One minute after application of the force, there shall be no electrical

contact between the insulated conductor. The electrical contact test shall be

made at 12V DC with a suitable indicator.

16.2 Retraction of Insulation: Retraction of insulation on insulated conductor

when cut a point, not less than one metre from one end of the insulated

conductor on the bobbin, the retraction on insulation on conductor at room

temperature shall not exceed 2.5 mm after one minute.

16.3 Shrink back of insulation: 200 mm specimen shall be cut from the centre of

1500 mm length and then reduced to 150 mm by trimming each end of the

specimen. The 150 mm specimen shall be placed in a convention type Air

circulating oven for 24 hours at a temperature of 100C 1C. The total

shrinkage from both ends shall be measured. A minimum of 6 or more

samples shall be tested at a time. The average shrinkage of 6 samples shall not

exceed 6.35 mm.

16.4 Cold Bend: 10 samples of the insulation material on the conductor shall be

tested in accordance with ASTM D-1047 after conditioning at a temperature of

-40C for 1 hour with mandrel diameter equal to the diameter of the insulated

conductor. There shall not be more than one failure out of 10 samples.

16.5 Thermal Stress Cracking: 10 lengths of insulated conductor of 10 cms each

removed from the extruder shall be wrapped on their own diameter with a

minimum of 10 contiguous turns closely wound in a length of 2 cm at 70C

1C for 14 days. After the period they shall be removed from the oven and

observed for cracks with naked eye. There shall be no cracks.

16.6 The insulated conductor shall be subjected to spark test at 3KV AC (RMS) or

4.5 KV DC for all conductor sizes. There shall not be more than one spark-

over per 5 Km of the insulated conductor, when assessed on a monthly basis

on the insulating line. The test will be at the extrusion stage.

17. COMPATIBILITY OF INSULATION AND FILLING COMPOUND:-

17.1 Absorption of filling compound: For this test 15 cm length of insulation

carefully removed from any conductor shall be weighed (about 2 gm) correct

to 1 mg. The lengths (suitably coiled and bent, if necessary); shall be placed in

a test tube or beaker full of filling compound with its ends 1 cm. above the

level of the compound and maintained at 70C 1C for 14 days. At the end

of this period, the insulation sample shall be weighed accurately. Increase in

weight shall be more than 10%.

17.2 Elongation and Tensile strength: 20 length of insulation shall be carefully

removed from any conductor and made into 2 sets of 10 each. The first set

shall be tested on a Tensile testing machine keeping 50 mm between the grips

and extending these at the rate of 250 50 mm per minute. The percentage of

elongation at break and the breaking load for the 10 lengths shall be noted and

the average worked out. These values shall not be less than 300% and 100

kg/cm sq. respectively.

The second set of 10 samples shall be aged in a test tube or beaker full of

filling compound and maintained at 70C 1C for 14 days. after aging as

above, the 10 lengths shall be tested in a tensile testing machine for tensile

properties in a similar manner as above. The average percentage elongation at

break and tensile strength after aging shall not change by more than 30% and

15% respectively of the values before aging.

17.3 Environmental Stress Cracking: 10 lengths of insulated conductor of 150

mm each removed from the extruder, shall be immersed in filling compound

for 24 hours at 70C 1C and insulated conductors will then be removed

from the compound and wiped clean. They will then be wrapped round its

own diameter for a minimum of 10 contiguous turns closely wound in a length

of 2 cm of insulated conductor. They will then be suspended in an air oven

maintained at 70C 1C for 14 days. at the end of this period they will be

removed from the oven and observed for cracks with naked eye. There shall

be no cracks.

18. TESTS FOR POLY-AL LAMINATE:-

18.1 Thickness: Thickness of Aluminium tape and polythene coating shall conform

to the requirements of cl.10.0.

18.2 Peel Strength: Peel strength of the polythene from the aluminium tape shall

not be less than 25 gm per mm width when tested in accordance with

Annexure ‘A’ (III).

19. TESTS ON COMPLETED CABLES:

19.1 Drip Test: When tested as in Annexure ‘A’(III) there shall be no dripping

of filling compound.

19.2 Oxidation Induction Test: The induction time in oxygen with a copper pan

tested by the method in Annexure ‘A’(V) shall not be less than 30 minutes for

each colour of insulation removed from the conductor of the completed cable.

20. TEST FOR COMPOSITE SHEATH AND JACKET FROM

COMPLETED CABLE:

The components removed from the cable sheath and jacket shall be capable of

meeting the following requirements:

20.1 Bond Strength: The bond strength of the poly-al laminate to the

polythene sheath and at the overlap shall meet the requirements indicated in

Annexure ‘A’ (III).

20.2 For the tests in this specification, the polythene sheath shall be stripped of the

laminate.

20.3 Tensile Strength and Elongation: The samples of polythene removed from

the cable sheath and jacket shall meet the following requirements when tested

in accordance with Appendix ‘A’ of BS-6234:

Tensile Strength Min. 70 Kg/cm2

Elongation Min. 300%

20.4 Environmental Stress Creaking: Test specimen without laminate cut from

the polythene sheath and jacket shall be subjected to an envirnmental stress

cracking test as described in ASTM: D-1693, when tested with 105 IGEPAL

solution at 50 1C for 48 hours. There shall be no failure.

20.5 Shrinkage Test: A specimen shall be cut from the cable sheath and

jacket, 50 mm long measured along the axis and 12 mm wide and the same

thickness as the cable sheath and placed in a convective type circulating air

oven operating at a temp. of 100C 1C for a period of 24 hours. at the end

of this period the shrinkage as measured in the lengthwise direction shall not

exceed 5%.

20.6 Carbon Black Content: The carbon black content of sheath and jacket

shall be determined as in BS: 6234, and shall be 2.5% 0.5% by weight.

20.7 Carbon Black Dispersion: The carbon black dispersion in sheath and jacket

shall conform to BS: 6234.

20.8 Oxidation Induction Test: The induction time in oxygen when tested with

copper pan as per the method in Annexure ‘A’ (V) shall not be less than 15

minutes.

20.9 Thickness of Sheath and Jacket: The nominal, minimum and average

thickness shall be in accordance with cl. 11.0, Table-6 and Table-7 of this

specification. The variation between the maximum and minimum diameter at

any cross section of the sheath shall be as per cl. 11.2.

21. TEST ON RAW MATERIAL OF POLYTHENE SHEATH AND

JACKET:

21.1 The tests on armouring shall be in accordance with cl. 12.3 of this

specification.

22.2 The steel tapes removed from the completed cables shall meet the following

requirements:

i) The steel tape thickness (including zinc coating ) shall be as per cl. 12.2.

ii) The tensile strength shall be less than 250 to 450 N/ mm2

iii) The elongation shall not be less than 10%.

iv) The steel tape shall withstand two dips of one minute each when tested in

copper sulphate solution prepared as per IS: 2633.

v) The steel tape should be free from rust/ bare patches.

vi) Steel tape shall be tested for mass of zinc coating as per IS: 10810 (Part 41) –

1984 and value shall not be less than 210 gm/m2 on each side.

22.3 The steel tape from raw material lot shall meet the following requirement of

tests, conforming to IS: 3975:-

vii) The steel tape thickness (including zinc coating ) shall be as per cl. 12.2.

viii) The tensile strength shall be less than 250 to 450 N/ mm2

ix) The elongation shall not be less than 10%.

x) The steel tape shall withstand two dips of one minute each when tested in

copper sulphate solution prepared as per IS: 2633.

xi) The steel tape should be free from rust/ bare patches.

xii) Steel tape shall be tested for mass of zinc coating as per IS: 10810 (Part 41) –

1984 and value shall not be less than 210 gm/m2 on each side.

23. WATER PENETERATION TEST:

23.1 This test shall normally be conducted at the sheathing stage. In case the cable

has already been armoured or jacked, the bedding tape, the steel tape and

jacket, as applicable, have to be removed at the point of application of water.

23.2 One metre of the cable shall be supported horizontally and one metre head of

water applied at ambient temperature. The test duration shall be indicate as

below:

Type tests 14 days

Acceptance tests for bulk supplies 7 days.

24. CABLE BEND TEST:

24.1 This test shall be carried out with the armouring removed in case of armoured

cable or an unarmoured cable sample.

24.2 The cable sample shall be coiled around a mandrel having a diameter of 12D

for at least one complete turn, ‘D’ being the diameter of the cable under test.

The sample shall then be straightened and observed. The sheath shall not

ripple and there shall be no damage to sheath.

25. ELECTRICAL REQUIREMENTS:

25.1 Continuity Test:

25.1.1 All the conductors in the complete cable shall be tested for continuity and

absence of crossed pairs and contacts. No conductor shall have contact with

poly-al tape.

25.2 Conductor Resistance:

25.2.1 The resistance of conductors and the tolerance of individual values shall meet

the requirements of Table-1. The temperature correction factor is indicated in

Table-2. The temperature corrections for resistance shall be made using the

following equation:

Resistance at tC

Resistance at 20C = -----------------------

[1+0.00393 (t-20)]

25.3 RESISTANCE UNBALANCE:

25.3.1 The conductor resistance unbalance (RU) shall not exceed the values

indicated below:

Conductor Size Percentage Unbalance

Maximum Average Individual Maximum

0.50 mm 1 2.5

0.63 mm 1 2.0

0.90 mm 1 2.0

25.3.2 The percentage RU of any individual pair tested shall be calculated as

followings:

R1 - R2

% Resistance Unbalance = ------------- X 100

R1 + R2

Where R1 & R2 are the resistance of individual conductors of the pair under

test & R1 is higher than R2.

25.4 POLY-AL TAPE: The poly-al tape shall be tested for continuity, and its

resistance value noted.

25.5 MANUAL CAPACITANCE:

25.5.1 The average mutual capacitance of the pairs in the cable when measured at

800 to 1000Hz shall be 52 4.5 nF/km.

25.6 CAPACITANCE UNBALANCE:

25.6.1 The pair to pair capacitance unbalance measured at 800Hz to 1000Hz for all

combinations of pairs in each unit/ super unit in cable shall not exceed the

following limits:

Average 50 pf/km

Individual combination 200 pf/km.

25.6.2 The pair to ground capacitance unbalance ( at 800 Hz – 1000 Hz) shall not

exceed the following values:

Average 750 pf/km

Individual 3,000 pf/km.

25.6.3 The measurement shall be corrected as follows:

i) Capacitance unbalance pair to pair measured value shall be divided by

½ ( L/1000 + L/1000)

Where, L is the length of the cable tested in metres.

ii) Capacitance unbalance pair to ground - The measured value shall be divided

by 1000 where L is length of the cable under test in metres.

25.6.4 Length less than 100 metres shall be assumed as 100 metres.

25.7 CROSS TALK: Equal Level Far End Cross Talk (ELFEXT) and

Near End Cross Talk (NEXT) at 150 KHz of the cable shall meet the

requirements indicated in 25.7.1 and 25.7.2 respectively. The measurement

will be made on all combinations of pairs in cable as indicated in cl. 25.6.1.

25.7.1 ELFEXT: The individual and RMS value shall be better than 55 dB/Km

and 67.8 dB/km respectively.

RMS (dB) = 10 log 10 [ { 10 – m (i, j) /10} / n ]

where m(i, j) = Cross-talk values between the i and j pairs.

n = Number of pair combinations.

25.7.1.1 For lengths other than one km, the measured value shall be corrected

by 10 log 10/ L100, L being the cable length tested in metres.

25.7.2 NEXT: The individual values between pairs shall be better than 55 dB,

when corrected to unit length of 1 km.

25.7.2. 1NEXT CORRECTION: No correction is necessary if cable length

of 300 metres or more are tested. For other lengths the NEXT value shall

be corrected with the following:

Nx = No – 10 log10 [ ( 1-e-4.a.1x) / (1-e-4.a.1o) ]

where, a = Average attenuation in Naperies per km

Nx = Next in dB corrected to a unit length of 1 lm.

No = Measured value for length (10) in dB.

1x = 1 km

1o = Length of cable tested in km

e = 2.71828

25.7.2.2 Lengths less than 150 meters shall not be tested for these parameters.

25.8 ATTENUATION: The average attenuation of the pairs at 150 KHz shall

not exceed the value listed below at 20C:-

0.5 mm 8.25 dB/km

0.63 mm 6.3 dB/km

0.90 mm 4.4 dB/km.

Temperature correction for attenuation will be done as:

Attenuation 20C = [Attenuation at TC] / [1+0.0018 (T – 20) ]

25.9 Reduction Factor: The intrinsic reduction factor for cable sizes 10 pair to

200 pair, when measured in accordance with cl. 507 of VDE Specification No.

0472/ 6.65 shall not be higher than 0.5 in the field intensity range of 50 to

450V/km. This shall be conducted on armoured cable only.

25.10 HIGH VOLTAGE TEST (EIELECTRIC STRENGTH) :-

25.10.1The insulation between conductors shall be capable of withstanding for three

seconds, a DC potential of 2.4 kv for 0.5 mm and 3.5 kv for 0.63 mm and 0.9

mm dia conductor.

25.10.2The insulation between the shield and the conductors in the core shall

withstand for 3 second a DC potential of 5kv for 0.5mm and 10kv for 063 and

0.9 mm dia conductor.

25.11 INSULATION RESISTANCE:

25.11.1The insulation resistance measurements shall be made with DC voltage of

magnitude not less than 500v after steady electrification for one minute. The

insulation resistance between each conductor in the cable and the other

conductors connected together with the aluminium foil and earthed shall not

be less than 5000 Mega ohms – km ( cable length in km x observed insulation

in Mega ohms ) at room temperature.

26. INSPECTION AND TESTING:

26.1 Unless otherwise specified, all tests shall be carried out under ambient

atmosphere condition.

26.2 Type Tests: The following shall constitute type tests and shall carried out

once in three years or earlier at the discretion of the inspecting authority. At

least two cable drums each of different conductor dia. and different pairs

comprising of one of size 10 pairs of 50 pairs and another of size 20 pairs or

100 pairs shall be taken for type test from the lot consisting of two drums each

of two different sizes. There shall not be any failure in both the drums

selected for prototype evaluation.

26.2.1 Test on raw materials:

26.2.1.1 Polythene for conductor insualtion (cl. 4.0)

a) Density (cl.4.3,i)

b) M.F.I. (cl.4.3,ii)

c) Dissipation factor (cl.4.3,iii)

d) Dielectric constant or permittivity (cl.4.3,iv)

26.2.1.2 Filling compound (Petroleum Jelly) (cl. 15.0)

a) Stability (cl. 15.1)

b) Colour (cl. 15.2)

c) Handling (cl. 15.3)

d) Volume resistivity (cl. 15.4)

e) Permittivity (cl. 15.5)

f) Flash point (cl. 15.6)

26.2.1.3 Poly-Al tape (Screen) (cl. 18.0)

a) Thickness (cl. 18.1)

b) Peel Strength (cl. 18.2)

26.2.1.4 Polythene for sheath and jacket (cl. 11.0)

a) Melt Flow Index (cl. 11.0)

b) Density (cl. 11.0)

c) Antioxidant (cl. 11.0)

26.2.1.5 Galvanised Steel Tape (cl. 22.3)

a) Thickness (cl. 22.3)

b) Tensile strength (cl. 22.3)

c) Elongation (cl. 22.3)

d) Dip test (cl. 22.3)

e) Mass of zinc coating (cl. 22.3)

26.2.2 Test on Insulated Conductor (cl. 16.0): The sample for these tests shall be

taken from bobbins of the extruded insulated conductors, used for

manufacturing cable for type test. These tests shall be carried out for each

colour of insulation.

a) Resistance to compression (cl. 16.1)

b) Retraction of insulation (cl. 16.2)

c) Shrink back of insulation (cl. 16.3)

d) Cold bend (cl. 16.4)

e) Thermal stress cracking (cl. 16.5)

f) Absorption of filling compound (cl. 17.1)

g) Elongation and Tensile strength (cl. 17.2)

h) Environmental stress cracking (cl. 17.3)

26.2.3 Tests on conductor (cl. 3.0): The samples for these test shall be taken from

the bobbins of insulated conductors.

a) Conductivity of copper (cl.3.1)

b) Resistance of joints in conductor (cl.3.2.1)

c) Tensile strength of joints in conductor (cl.3.2.2)

26.2.4 Test on completed cable:

i) COPPER CONDUCTOR

a) Dimensions (cl. 14.1.1)

b) Annealling (cl. 14.1.2)

ii) POLY-AL-TAPE:

a) Overlap of poly-al tape (cl. 10.1)

b) Thickness of composite tape (cl. 10.1)

c) Bond strength between

i) Poly-al at overlap (cl. 20.1)

ii) Poly-al & sheath (cl. 20.1)

iii) POLYTHENE SHEATH & JACKET: The following tests shall be

conducted on the samples taken from sheath and jacket both from finished

cable.

a) Tensile strength & % elongation at break (cl. 20.3)

b) Environmental stress cracking resistance (cl. 20.4)

c) Shrinkage (cl. 20.5)

d) Carbon black content (cl. 20.6)

e) Carbon black dispersion (cl. 20.7)

f) Oxidation Induction Test (cl. 20.8)

g) Thickness of sheath (cl. 11.3)

h) Diameter over sheath (Table-5)

i) Variation between the maximum and (cl. 11.2)

minimum diameter over sheath at any cross section

j) Thickness of jacket (Table-7 & cl. 13.2)

k) Diameter over jacket (Table-5)

1v) BEDDING TAPE:

a) Width (cl. 12.1)

b) Overlap (cl. 12.1)

v) GALVANISED STEEL TAPE:

a) Gap in application of first tape (cl. 12.2)

b) Overlap of second tape over first one on either side (cl. 12.2)

c) Thickness (cl. 22.3 i)

d) Tensile strength (cl. 22.3 ii)

e) Elongation at break (cl. 22.3 iii)

f) Dip test (cl. 22.3 iv)

g) Mass of zinc coating (cl. 22.3 vi)

vi) COMPLETED CABLE:

a) Drip test (cl. 19.1)

b) Cable bend test (cl. 24.0)

c) Water penetration test (cl. 23.0)

vii) ELECTRICAL TEST:

A) LOW FREQUENCY (AUDIO FREQUENCY RANGE TESTS):

a Continuity of conductors, absence of crossed pairs and contacts with

poly-al tape. (cl.25.1)

b) Conductor Resistance (cl.25.2)

c) Resistance unbalance (cl.25.3)

d) Continuity of poly-al tape i.e. resistance (cl.25.4)

e) Mutual capacitance (Pair/average) (cl.25.5)

f) acitance unbalance (Pair to pair) (cl.25.6.1)

g) Capacitance unbalance (pair to ground) (cl.25.6.2)

h) Dielectric strength (High voltage) between conductors. (cl.25.10.1)

i) Dielectric strength between all conductors and shield. (cl.25.10.2)

j) Insulation resistance. (cl.25.11)

B) HIGH FREQUENCY (150 KHz FREQUENCY RANGE) TESTS:

a) Equal level far end cross-talk (ELFEXT) (cl.25.7.1)

b) Near end cross talk (cl.25.7.2)

c) Attenuation (cl.25.8)

C) REDUCTION FACTOR TEST AT 50 Hz (cl.25.9)

27. ACCEPTANCE TEST:-

27.1 Acceptance test shall comprise the following:

a) Visual examination (cl.29)

b) Test for conductor (cl.14.0)

c) Test on polythene insulation/ insulated conductor (cl.16.3)

d) Test on Poly-al tape (cl.10.1)

e) Test on polythene sheath & jacket (cl. 20.0) except (cl.20.1)

f) Test on bedding tape (cl.10.1)

g) Test on galvanised steel tape (cl. 26.2.4,v)

h) Test on completed cable (cl. 26.2.4, vi b & vi c)

i) Electrical test (cl.25.0)

27.1.1 Any other test as required by the inspecting authority to ensure that offer is in

conformity with the requirement of the specification.

28. ROUTINE TESTS:-

28.1 The following shall constitute the routine tests. The manufacturer shall have

the system to undertake the following routine tests during in process as well as

completed cable stages. As far as possible, the test results of these tests shall

be well documented and shown to the inspecting authority as and when asked

by the inspecting authority.

a) Visual inspection (cl.29.0) = 100%

b) Dimensional check (cl.10..1, 11.2,11.3, 12.2, 12.3, 13.2, 20.9) = 100%

c) Spark test (cl.11.4, 13.4, & 16.6) = 100% to be carried out for entire

lot of material offered for inspection in the form of flow chart in such a

way that link up/ back trace history of each drum shall be identified

from insulation stage to the final jacketing stage.

d) Electrical test (cl. 25.except cl.25.2) = 20%

(cl.25.2) = 100%

e) Reduction factor (cl.25.9) = 20%

f) Water penetration (cl.23.0) = 100%

g) Bend test (cl. 24.0) = 20%

29. VISUAL EXAMINATION:-

29.1 The physical condition of the cable shall be visually examined by transferring

it to another drum. The cable shall be reasonably circular throughout its

length and shall be free from any physical defects.

29.2 The cable shall be visually examined to meet the requirement as specified

under cl.33 i.e. marking over the cable jacket of unarmoured cable.

30. PACKING:-

30.1 The direction of rotation of the colour scheme of the units in the cable shall be

indicated by bends of red colour in the clockwise direction. Suitable self

adhesive tapes may be used for the purpose.

30.2 The cable drums shall have cables of lengths 500M 10% unless single

longer lengths are specified by individual purchaser for specific application.

30.3 Short length upto 55 of the ordered quantity subject to any single short length

not less than 150 meter shall be permissible unless otherwise specified by the

purchaser.

30.4 The lagging shall be further strengthened by steel straps bound

circumferencially over the drum. The tolerance of 10% on the nominal

drum length for all sizes shall be permitted.

30.5 Cable shall be wound on strong wooden drums conforming to TEC Spec. No.

G/CBD-01/02. Nov94 of suitable fungicide. Nails used in the drums shall be

properly clinched.

30.6 The drum shall be fitted with spindle plate of minimum thickness 3 mm to

take 75 mm round steel spindle.

30.7 The dia. of the yoke of the drums used shall not be less than 20 times the

overall dia. of the cable.

30.8 Both ends of the cable shall be kept inside the drums and shall be located to

enable easy access for the test. The battons on the drum to gain access to the

cable ends shall be painted red.

30.9 Cable ends shall be fastened and secured that the cable turns do not unravel,

get loose or displaced.

30.10 The drum shall be effectively lagged with stout and closely fitted battens after

cable tests so as to prevent any damage to the cable during transit or storage.

31. SEALING OF ENDS:-

31.1 Immediately after completion of the electrical tests, the ends of the cable shall

be sealed by enclosing them in rubber or PVC caps of wall thickness not less

than 1.8 mm. The caps shall be robust construction and tight fit. The caps

shall be coloured black and shall be secured to the sheath/ jacket with

appropriate hose clips or ties or black adhesive tape or heat shrinkable sleeves.

Alternatively, thermoshrinkable capes of adequate wall thickness may be used

to seal the ends.

31.2 After the cable is passed & inspected by RDSO, the ends of the cable may be

sealed as above, and hot stamping with RDSO stamp at the ends shall be done.

32 SAMPLING:

32.1 All cable drums having cable of same conductor dia. same number of pairs

and similar construction shall constitute a lot.

32.2 Drums shall be chosen at random from the lot for taking samples. The

samples will be cut from these cable drums. The length of samples required

for various tests shall be according to the requirements laid down in various

tests clause.

32.3 The number of drums and samples from which test pieces will be taken for

various tests shall be as per Table – 7.

33 MARKING:-

33.1 Manufacturer’s Identification & Sequential Length Marking :

To enable proper identification of the cable, the following marking shall be

embossed, engraved or printed on the polythene jacket in case of armoured

cable, and on the sheath for unarmoured cable. All the marking shall be in

white or yellow colour.

a) Name/ Trade mark of the manufacturer,

b) Year of manufacture (Calebder year)

c) No. of pairs/ conductor size (Ex.100 prs/0.63 mm)

d) Length (sequential marking )

e) IRS Specification No. IRS: TC 41.

f) Cable drum No.

33.2 The marking shall be clear, distinct and visible to the naked eye from a

distance of about 1 metre; the size of marking shall be minimum 3 mm.

33.3 The marking shall be at intervals of one metre and shall be throughout the

length. he running length marking is critical.

33.4 The finished cables and components shall meet all the test requirements

specified later in this specification.

33.5 The following information shall be stenciled on the drums.

a) Manufacturer’s name, brand name of trade mark,

b) IRS Specification No. IRS: TC 41-97,

c) Type of table,

d) No. of pairs and dia. of conductor,

e) Length of cable on the drum,

f) Direction of rotation of the drum (by means of an arrow),

g) Approximate gross weight,

h) Country and year of manufacture,

i) Drum No.

TABLE - 1

CONDUCTOR DIAMETER, RESISTANCE AND ELONGATION

Nominal conductor

diameter (mm)

Resistance per

km of cable

conductor at

20C (ohms)

Tolerance

on

resistance

(ohms/km)

Minimum % elongation

of conductor samples

taken from completed

cable.

0.50 mm 86 6 15

0.63 mm 58 4 18

0.90 mm 28 2 18

TABLE - 2

CORRECTION FACTOR FOR CONDUCTOR RESISTANCE

Temp. in C at

which conductor

resistance is

measured

Multiplier constant

for conversion to

20C

Temp. in C at

which conductor

resistance is

measured

Multiplier constant

for conversion to

20C

10 1.0409 31 0.9586

11 1.0367 32 0.9550

12 1.0367 33 0.9514

13 1.0283 34 0.9478

14 1.0241 35 0.9443

15 1.0200 36 0.9408

16 1.0160 37 0.9374

17 1.0119 38 0.9339

18 1.0079 39 0.9305

19 1.0039 40 0.9271

20 1.0000 41 0.9238

21 0.9961 42 0.9204

22 0.9922 43 0.9171

23 0.9883 44 0.9138

24 0.9845 45 0.9105

25 0.9807 46 0.9073

26 0.9770 47 0.9041

27 0.9732 48 0.9009

28 0.9695 49 0.8977

29 0.9658 50 0.8945

30 0.9622

TABLE - 3

COLOUR CODE FOR TAPE OR BINDER FOR

UNIT IDENTIFICATION

Unit Number Colour of biner

1 Blue

2 Orange

3 Green

4 Brown

5 Grey

TABLE - 4

COLOUR CODE FOR CONDUCTOR INSULATION

Pair No. 1st wire ( tip) 2

nd wire ( ring )

1 White Blue

2 White Orange

3 White Green

4 White Brown

5 White Grey

6 Red Blue

7 Red Orange

8 Red Green

9 Red Brown

10 Red Grey

11 Black Blue

12 Black Orange

13 Black Green

14 Black Brown

15 Black Grey

16 Yellow Blue

17 Yellow Orange

18 Yellow Green

19 Yellow Brown

20 Yellow Grey

NOTES:

a) In 10 pair units, cables colours code specified for pairs, 1 to 10 shall be used.

b) In 20 pair units, colour code specified for pair 1 to 20 shall be used.

c) The number of pairs with respect to the colour scheme is only for the purpose

of identification of pairs, the actual numerical sequence of the pairs may not

be insisted upon.

TABLE - 5

DIAMETER OVER SHEATH AND JACKET

No. of pairs in

cable

Maximum Diameter ( mm )

0.5 mm 0.63 mm 0.9 mm

Nominal Actual Sheath

(mm)

Jacket

(mm)

Sheath

(mm)

Jacket

(mm)

Sheath

(mm)

Jacket

(mm)

10 10 12.7 19.0 15.3 21.5 17.5 23.6

20 20 17.0 24.0 19.0 26.0 25.0 32.0

50 50 22.0 29.0 25.5 32.5 35.0 42.5

100 100 28.0 36.0 34.0 42.0 47.0 55.5

200 200 37.5 45.5 46.0 54.0 65.0 73.0

NOTE:

The above values are tentative and meant for the manufacturer’s guidance.

These values are subject to modifications after further feed back is received

from the manufacturers and users.

TABLE - 6

POLYTHENE SHEATH THICKNESS AND SPARK TEST VOLTAGE

Specified diameter of cable

over sheath (mm)

Nominal sheath

thickness (mm)

(excluding Poly-

Al laminate)

Spark test voltage KV

Above Upto RMS AC DC

- 30 2.0 11 17

30 40 2.2 11 17

40 50 2.4 11 17

50 60 2.6 13 20

60 70 2.8 13 20

TABLE - 7

NOMINAL THICKNESS OF JACKET AND SPARK TEST VOLTAGE

Specified diameter of cable

over polythene jacket

Nominal thickness

of polythene jacket

Spark test voltage KV

Above Upto RMS AC DC

- mm 46 mm 1.4 mm 8 12

46 mm 64 mm 1.8 mm 10 15

64 mm - mm 2.2 mm 11 17

TABLE - 8

SAMPLING PLAN FOR ACCEPTANCE TESTS

S. No. Inspection item &

clause No.

Sample size

(No. of drum)

No. of test pieces to be

taken from each drum.

1. Dimensions (cl. 10.1,

11.2, 11.3, 12.1, 12.2,

13.2, 20.9)

10% subject to

minimum of 1

drum

10 Pairs

2. Visual examination

(cl.29.0)

One drum

(min.)

One drum of each size

of conductor dia.

3. Annealing of copper

conductors (cl. 14.1.2)

5% subject to

min. of 1 drum

10 Pairs

4. Tensile strength & %

elongation of sheath &

jacket (cl. 20.3)

- Do -

2 specimen each of

sheath & jacket from

each size of conductor

dia.

5. Tensile strength & %

elongation at break of

galvanised steel tape

(cl.22.2 except vi)

- Do -

2 specimen each of

inner and outer steel

tape of the cable for T.S.

elongation at break &

dip test.

6. ESCR of sheath &

jacket (cl. 20.4)

1 drum ( min.) 2 specimen each of

sheath & jacket from

each size of conductor

dia.

7. Shrinkage of sheath &

jacket (cl. 20.5)

1 drum (min ) - Do -

8. Carbon black content &

carbon black dispersion

(cl. 20.6 & 20.7)

1 drum (min.) 1 specimen each of

sheath & jacket from

any drum of the lot.

9. Shrinkage back of

insulation (cl.16.3)

1 drum (min.) 6 test specimen from

each colour of insualtion

and each size of

conductor dia.

10. Conductor resistance

(cl. 25.2)

20% subject to

minimum of 2

drum

100%

11. Resistance unbalance

(cl. 25.3)

20% subject to

minimum of 2

drum

100%

12. Mutual capacitance (cl.

25.5)

10% subject to

min. of 2

samples.

100%

13. Capacitance unbalance

(cl. 25.6)

10% subject to

min. of 2

samples.

100%

S. No. Inspection item

& clause No.

Sample size (No. of

drum)

No. of test pieces to be

taken from each drum.

14. Dielectric strength

(cl. 25.10)

20% subject to min.

of 2 samples.

All pairs ( Bunch

method)

15. Insulation

resistance

(cl.25.11)

20% subject to min.

of 2 samples.

All pairs ( Bunch

method)

16. Reduction factor

(cl.25.9)

5% subject to

minimum 1 sample.

2 conductors from

different binder & pairs

17. Water penetration

(cl.23)

10% One specimen from

each drum

18. Cable Bend test

(cl. 24)

5% subject to

minimum of one

sample.

One specimen from

each drum

19. Cross talk (cl.

25.7)

10% subject to

minimum of 2

samples

100%

20. Attenuation (cl.

25.8)

10% subject to

minimum of 2

samples.

100%

TABLE - 9

SAMPLEING PLAN FOR TYPE TEST

I. RAW MATERIAL:

S.No Raw Material Cl. No.

of spec.

Test Sampling

1. Polythene for

conductor

insulation

4 a) Density

b) Melt Flow

Index

c) Dissipation

factor (power

factor)

1 sample from the

bag used for

manufacturing cable

for type test

- Do -

- Do -

2. Filling

Compound

15.1

15.3

15.4

15.5

15.6

Stability

Toxic/ dermatic

hazards

Volume

Resistivity

Permittivity

Flash point

- Do -

Compound

suppliers test

certificate to be

furnished

1 sample from the

Barrel used for

manufacturing cable

for type test.

- Do -

- Do -

Do - - Do -- Do - - Do -

S.No Raw Material Cl. No.

of spec.

Test Sampling

3. Poly-al tape

screen

18.1

18.2

Thickness

Peel strength

5 samples from the

coil used for

manufacturing cable

for type test.

- Do -

4. Polythene for

sheath and

jacket

11

a) Melt Flow

Index

b) Density

1 sample from the

bag used for

manufacturing cable

for type test.

- Do -

5. Galvanised

steel tape

22.3 i) Thickness

ii) Tensile

strength

iii) Elongation

iv) Dip test

5 samples from coil

used for

manufacturing cable

for type test.

- Do -

- Do -

- Do -

II. INSULATED CONDUCTORS (EACH COLOUR TO BE TESTED)

S. No. Cl. No. Test Sampling

1. 16.1 Resistance to

compression

No. of sets such that at least

one conductor for each colour

is tested.

2. 16.2 Retraction of insulation One sample from one bobbine

of each colour.

3. 16.3 Shrinkage back of

insulation

A minimum of 6 samples of

each colour.

4. 16.4 Cold bend 10 samples of each colour

5. 16.5 Thermal stress cracking 10 samples of each colour

6. 17.1 Absorption of filling

compound

One set ( approx. 20 samples)

per colour.

7. 17.2 Elongation and tensile

strength

10 samples of each colour

8. 17.3 Environmental stress

cracking

lour

III. IN-PROCESS TESTS:

S. No. Cl. No. Test Sampling

1. 3.2.1,

3.2.2

Joints in conductors for

resistance & tensile

strength

1 joint of each colour of

insulated conductor to be

tested

2. 16.6 Spark test on insulated

conductor

Factory records to be checked

up

3. 11.4 Spark test on sheath - Do -

4. 13.4 Spark test in jacket - Do -

IV. TESTS ON COMPLETED CABLES:

S. No. Cl. No. Test Sampling

1. 7.2 Colour, thickness & lay

of unit binder tape

1 cable drum

2. 10.1 Overlap of poly-al tape - Do -

3. 19.1 Drip test 2 samples (one from each

end) from offered cable drums

4. 19.2 Oxidation/ induction

test

1 sample each of each colour

of insulation from any one

drum

5. 20.1 Bond Strength between

Poly-al at over lap

ii) Poly-al & sheath

5 samples each each size of

conductor dia.

- Do -

6. 20 Polythene sheath

20.3 Tensile strength - Do -

20.3 Elongation at break - Do -

20.4 Environmental stress

cracking (ESCR)

2 samples each from sheath &

jacket of each size of

conductor dia

20.5 Shrinking - Do -

20.6 Carbon black content 1 sample from any one drum

20.7 Carbon black dispersion - Do -

20.8 Oxidation induction test - Do -

7. 12.1 Bedding Tape Tapes from each size of

conductor dia.

Width - Do -

Over lap - Do -

8. 26.2.4(v) Galvanised steel tape - Do -

a) Gap in the appli-

cation of the first tape

- Do -

b) Overlap of 2nd

tape

over the first one on

either side

- Do -

S. No. Cl. No. Test Sampling

c) Thickness - Do -

d) Tensile strength 2 samples each from inner &

outer steel tape of each size of

conductor dia.

e) Elongation at break - Do -

f) Dip test - Do -

g) Mass of zinc coating - Do -

9. 20 Polythene jacket

20.3 Tensile strength 2 samples each from jacket of

each size of conductor dia.

20.3 Elongation at break - Do -

20.4 Environmental stress

cracking (ESCR)

- Do -

20.5 Shrinkage - Do -

20.6 Carbon black content 1 sample from any one cable

drum

20.7 Carbon black dispersion - Do -

20.8 Oxidation induction test - Do -

10. 20.9 Thickness of sheath To be tested for each size of

conductor dia.

11. Table-5 Diameter over sheath - Do -

11.2 Variation between the

maximum and

minimum diameter over

sheath at any cross-

section

- Do -

12. 20.9 Thickness of jacket - Do -

13. Table-5 Diameter over jacket - Do -

14. 25.4 Resistance of poly-al

tape

- Do -

15. 14.1.2 Annealing of copper 10 pairs of each size of

conductor dia.

16. 25.10.1 Dielectric strength

between conductors.

All conductors of offered

drums for type test (Bunch

method)

17. 25.10.2 Dielectric strength

between all conductors

and shield.

- Do -

18. 25.7.1 ELFEXT 100%

19. 25.7.2 NEXT - Do -

20. 25.8 Attenuation 100%

21. 25.11 Insulation resistance Bunch method

22. 24 Cable bend test To be tested for each size of

conductor dia.

23. 25.1 Continuity test - Do -

24. 25.2 Conductor resistance 100% (all drums offered for

type test).

S. No. Cl. No. Test Sampling

25. 25.3 Resistance unbalance - Do -

26. 25.5 Mutual capacitance - Do -

27. 25.6.2 Capacitance unbalance

( pair to pair)

- Do -

28. 25.6.2 Capacitance unbalance

( pair to ground)

- Do -

29. 25.9 Reduction factor One specimen from each

drum of two different sizes/

conductor dia with two

conductors from different

binders and pairs.

30. 23 Water penetration test Two specimens from each

drum from top end and

bottom end for two different

sizes/ conductor dia.

31. 29 Visual examination 1 drum each of each size of

conductor dia.

IRS: TC 41-97

ANNEXURE – A

I. STABILITY TEST METHOD:

Experimental set up is as indicated in fig. 1. About 5 gms filling

compound is filled in a glass container with both ends open and held with the

axis of the container in a horizontal plan. The outer surface of the glass tube is

covered with a copper wire mesh to ensure uniform temperature and prevent

local hot sports.

This container is suspended vertically in (accurately weighted) test

tube so that it hangs freely. The temperature of the jelly is mentioned by a

thermometer. The test tube is now placed in a constant temperature bath

maintained at 65C 1C for 120 hours.

The compound shall remain intact in the container after 120 hours and

shall not show any separation of the constituents of the compound.

II. DRIP TEST:

The test specimen if 30 cm in length shall be cut from a completed

cable. One end of the sheath shall be stripped for approximately 5 cms and the

conductors with the jelly wiped clean shall be flared out a approximately 45

angle. The same shall then be suspended in air oven with a glass disc placed

directly below the flared and of the cable. The oven temperature shall be set at

65C 1C for a period of 24 hours. At the end of the test the glass disc shall be

examined for the presence of filling compound which might have dripped.

There shall be no dripping of filling compound.

III. PEEL STRENGTH FOR LAMINATE AND COMPOSITE SHEATH:

A parallel sided test piece 150 mm long and 13 to 16 mm wide of the

laminate or sheath shall be cut longitudinal from the laminate or sheath in one

operation using a sheath.

Test piece taken for testing the strength of the bond between the sheath

and aluminium tape shall exclude the overlap of aluminium foil. For small

diameter cables, it may not be possible to get sheath test pieces 13 cms wide.

In such cases test pieces of less width may be taken (excluded the poly-al

overlap).

Test pieces taken for testing the strength of the bond between the

interface of the aluminium tape at the seal shall include only the overlap of the

tape.

2. a) For testing peel strength of laminate only, separate the aluminium and

polythene tape at one end. Insert the aluminium in the fixed grip of the tensile

tester.

b) For testing bond strength of sheath, insert the aluminium in the fixed

grip and polythene sheath in the moving grip.

c) For testing bond strength of laminate at the overlap, insert the aluminium

tape in the fixed grip and the poly-al –poolythene sheath (other edge ) in the

grip. For cl. 4.0 a, b & c, the grip can be brought closer upto 3 cms. An

electric operated tensile tester shall be used. Rate of separation between grips

shall be 100 to 135 mm/min. and the steady force required to separate the

materials shall be noted.

3. Initial separation of the laminate or laminated sheath to facilitate insertion in

the grips can be made by immersing about 25 mm at the end of the test piece

in boiling industrial alcohol for about 30 seconds.

4. Sampling and Requirements:

a) Peel strength of the laminate raw material shall be 25 gms/mm width

(minimum). 5 samples shall be tested.

b) Bond strength of the laminate to sheath shall be 40 gms/mm

(minimum) and 60 gm/mm width (average) on 5 samples.

c) Peel strength of the laminate at overlap shall be the same as (b) above

on 5 samples.

IV. WATER PENETRATION TEST:

Sample Preparation: A piece of three meter length shall be cut from

the end of the cable. The inner one meter length as indicated in the fig. 3 shall

then be cut for test ensuring minimum disturbance to the cable core during the

cutting process. This inner 1 meter sample shall be subjected to the water

penetration test. The outer 2 meter shall not be used for this test. However,

for acceptance test, piece of only one meter length shall be taken from the end

of the cable drum for tests without discarding two meter length.

Testing Arrangement: This arrangement is shown in fig. 2 The sample

under test is kept straight in a horizontal plane on a test bench prepared for this

purpose. One end of the sample shall be connected suitably through a water

tight gland to a water pipe containing 1 meter head of water. The connection

shall be such that the cable sheath shall not be squeezed tight or shall in allow

leakage of water at this point. The other end of the cable shall be free

One meter head of water shall be applied for 7/ 14 days at ambient

temperature. The pipe connecting the water tank to the cable shall be vertical.

No air bubbles shall remain trapped in this pipe. Any bubbles that may be

present initially should be removed by agitating the water column using a thin

wire for this purpose.

The test shall be deemed to have started ensuring that the head of water is one

meter and all air bubbles have been eliminated. The sample shall not be

disturbed during the period under test. During this period, no water shall have

seeped from the cable sample. This test shall be conducted after inner sheath

stage.

V. OXIDATION INDUCTION TEST:

1. A short length section (approximately 30 cms) of 10 pairs or larger cable shall

be sealed at the ends and placed in an oven at a temperature of 68C 1C for

eight hours. The sample will then be allowed to cool down to room

temperature for a total of twenty four hours. After equilibration, five samples

shall be taken of each colour of insulation, each one from a different

conductor. Each sample shall be wiped clean of grease and foreign objects

using a dry cloth (without solvents). Each sample shall be wiped clean of

grease and foreign objects using a dry cloth ( without solvents). Each sample

shall be individually tested by means of a Differential Scanning Calorimeter

(DSC) or by Differential Thermal Analysis (DTA). The sample shall clean and

dry.

2. Instrument Test Procedure:

2.1 Cell Cleaning: Hold cell at approximately 400C for 10

minutes in nitrogen. Cell should be cleaned after standing overnight and

between testing of different formulations.

2.2 Temperature Calibration: The temperature scale should be adjusted

according to the instrument manual until the determined melting point of pure

indium metal is 156.6C at a heat rate of 5C per minute.

Engineering Notes:

Dupont 990 with DSC Cell: With instrument in isothermal mode, Calibrate

Stating Temperature dial may be set to a reading which results in a corrected

thermocouple read-out of 199C.

Perkin-Elmer DSC-I or DSC-2: Run several pure metal standards (e.g

indium, tin, lead, zinc) through their melting point at a heating rate of 5C per

minute. Plot melting temperature and interpolate to find the correct set point

for 199C. Repeat calibration required only adjustment for the indium melt

temperature.

2.3 Copper Pan Preparation: Prepare fresh copper oxide coating by holding

the pan in the flame of a fisher burner until it begins to glow (about 3

seconds). remove the pan from the flame and immediately cool in a Gentle

stream of air.

2.4 Sample Preparation: Remove the insulation from the conductor. Flatten the

resin to about 15 mils thickness (not critical), Clip samples to approximate

roundness, about 2mm in diameter.

Sample should weigh approximately 1 to 2 mg. position in centre of oxidized

copper pan, cover with clean 316 stainless steel screen ( 40 mesh) and crimp

the pan.

2.5 Nitrogen Purge: Place sample pan in instrument cell. Flush 5 minutes with

cylinder nitrogen at 60 10 cc per minute.

2.6 Oxidation Test: Rapidly increase sample temperature 20C/min. or

greater) from 100C or lower initial temperature, to 199C 1C. After

thermal equilibrium (steady recorder signal) simultaneously switch to 50

5CC/minute oxygen flow and start time-base recording. Other flow rates,

150cc/minute inclusive maximum, can be used. record rate flow used.

Oxygen should be equivalent to or better than 99.66 extra dry grade.

2.7 Induction Period: his oxygen induction point shall be recorded as time

zero, and the chart speed shall be sufficient to provide a clearly discernible

slope at the start of the exothermic shall continue until the exothermic peak is

produced. The intersection of the tangent of the exothermic sloped line with

the extended base line will be draw. The time from time zero to this

intersection point/ induction time. The insulation over the copper conduction

shall be capable of providing a minimum oxidation, Induction Time of thirty

minutes.

For this purpose one sample of each colour of any size/ gauge of the cable

should be taken as a specimen for testing for type approval.

APPENDIX - A

Information to be furnished by the purchaser:

The purchaser shall specify the following:

1. IRS/RDSO specification number.

2. Conductor size (cl. 2.1).

3. Size of the cable i.e number of pairs (cl.2.1)

4. Quantity.

5. Special length of the cable required in a drum, if any (cl. 30.2)

NOTE:

As an example the purchaser should mention in the indent/ purchase order

like:

1. 50 pair, 0.5 mm conductor dia. armoured, PIJF U/G telephone cable as per

IRS: Specification No. IRS: TC 41-97. The quantity is to be written separately

in the quantity column.

2. 10 pairs, 0.63 mm conductor dia. unarmoured, PIJF telephone cable as per

IRS: Specification No. IRS: TC 41-97.

APPENDIX - B

The information to be supplied and instruction to be followed by the

manufacturer.

The manufacturer should submit the following to the inspecting authority

when the material is ready for inspection:

1. Copy of all the test results of the routine tests as specified in cl. 28.0 of the

specification.

2. Type of polythene used for conductor insulation, cable sheath and jacket,

Galvanised steel tape, Poly-Al tape etc.

3. Type of jelly used as filling compound.

4. Validity of type approval granted by RDSO/Lucknow.

NOTES:

i) All reasonable/ complete facility considered necessary by the inspecting

authorities for the inspection of the cables shall be supplied by the

manufacturers free of cost.

ii) In case the inspecting authority observed as a result of the test carried out by

him that the recorded test results supplied to him are not reasonably accurate

for the lot offered for the inspection, he may reject the complete lot at his

discretion and call upon the manufacturer to have the cable type tested before

any further supplies are inspected or accepted.